混凝土疲劳寿命规律预测新方法

A new method for estimating fatigue life distribution law of concrete

基于混凝土疲劳寿命既服从对数正态分布，又服从两参数威布尔分布这一前提，由概率论中特征函数出发研究两种分布的逼近性，得到了两种分布参数之间的关系式．在理论上，沟通了两分布间的联系，藉此可利用对数正态分布参数估计威布尔分布参数，从而得到了一种新的两参数威布尔分布的估计方法．此外，在已知混凝土平均Ｓ－Ｎ关系的前提下，提出了混凝土对数疲劳寿命标准差与应力水平呈近似线性的假设；利用提出的参数估计方法，研究了任意应力水平下混凝土疲劳寿命分布的概率模型。

Firstly, based on the assumption that lognormal distribution is approximation to Weibull distribution in fatigue life of concrete, the relationship between two types of distribution parameters above is studied theoretically from their characteristic functions. And, a new method for estimating two parameters of Weibull distribution from lognormal distribution parameters is obtained. Secondly, a simple method determining the mean S N relationship is developed. And, the hypothesis that the standard error of lognormal fatigue life is proportional to the stress levels is verified by the statistic analysis of test data. Thirdly, according to the above studies, the probabilistic model of fatigue life distribution of concrete is proposed. Lastly, it is suggested that the results be used to realistic fatigue reliability analysis and design of concrete stuctures.